There's nothing complicated about it. Culture=Religion+Politics. Eliminate religion, or eliminate politics, and you get anarchistic disorder and chaos: the opposite of culture.

Everybody instinctively knows that the "best" cultures are the most moral, peaceful, civil, well mannered and refined. But where all that cultural "goodness" comes from is less intuitive, and less thought about within any culture, as that culture ages. It's just expected; nobody gives it much thought; it's just the way things are.

And it should not be that way, if good culture is to endure. The reasons for cultural goodness must be taught to younger generations, or they will simply slip away, and the "goodness" of culture with them. So, why is a culture "good", and how does that goodness come to be?